The present invention relates to a golf club head, more particularly to a hollow structure having a specific shape capable of increasing the depth of center of gravity and the moment of inertia of the head.
It is effectual for improving the directionality of a hit ball to deepen the center of gravity of the head and to increase the moment of inertia. By increasing the depth of the center of gravity, the club face is increased in the sweet spot area and as a result the average carry distance can be increased. By increasing the moment of inertia, movements of the head caused by the counter-reaction to hitting of a ball is decreased, and the directionality can be improved.
Conventionally, driver or wood golf clubs have pear-shaped heads as shown in FIG. 10. Nowadays, in order to increase the moment of inertia and to deepen the center of gravity, very large-sized metal wood heads and metal/FRP hybrid wood heads are marketed. Even in such large-sized current heads, the shapes are pear-shapes, following a tradition.
In the case of pear-shaped heads, when obtaining a deep center of gravity and an increased moment of inertia, a certain degree of increase of the head volume and a certain degree of increase of the head weight are inevitable. As a result, the head speed during swing tends to decrease. As the head volume increases, a weight margin available for adjusting the position of the center of gravity is decreased, therefore, the flexibility of designing the weight distribution is lost. As a result, it becomes difficult to increase the depth of the center of gravity.